(1) Field of the Invention
The present invention relates to a novel preservative composition for protecting foodstuffs, agricultural products, marine products, livestock products, furs, natural fibers, paper products, and processed products thereof from the adverse effects of microorganisms and insects and the undesirable influences thereon occurring in the presence of oxygen.
(2) Description of the Related Art
As the agent to be used for protecting foodstuffs and the like from the adverse effects of microorganisms or insects by direct incorporation or impregnation, a variety of so-called mildewproofing agents, mothproofing agents and antiseptic agents are known. All of these agents, however, are chemical substances which are more or less toxic, and when introduced into human bodies orally or by inhalation, have undesirable effects on the health.
An oxygen-scavenging composition comprising a metal powder or granule such as iron powder and an alkali metal halide or alkaline earth metal halide (for example, sodium chloride) as an oxidation accelerator has been used as a preservative agent for foodstuffs and the like. More specifically, this oxygen-scavenging composition is packaged in a gas-permeable vessel, and the packaged composition and a foodstuff, an agricultural product, a fur, a natural fiber, a paper product or a processed product are sealed in a gas-barrier vessel, and in this manner, the above-mentioned oxygen-scavenging composition is widely and practically used as a preservative agent for protecting the product from damage by microorganisms such as mildew, insects such as weevils, and oxygen. When, however, the oxygen-scavenging composition is used for a product for which softness is required, such as bread, a Japanese steamed cake or fur, hardening occurs and the taste or texture is degraded. Moreover, in the case of seaweeds such as Undaria pinnatifida, browning is caused and the commercial value is lost. Furthermore, the metal surface reacts with water to form a metal oxide and generate hydrogen, and if iron is used as the metal, iron reacts with oxygen or moisture in air to form an oxide and cause rusting, and therefore, red rust spots appear and there is a risk that a fine rust will leak into the vessel.
A preservative composition comprising an ethanol vapor-generating member was proposed (see Japanese Pat. No. 1,046,326) and has been practically used. However, this preservative composition has a problem such that in the case of a foodstuff having a very high water activity, a large amount of the ethanol vapor-generating member must be used.
Utilization of an oxygen-scavenging agent and an ethanol vapor-generating member in combination was tried, but this could not be put into practical application because ethanol vapor introduced in the deoxidizing reaction system (in the deoxidizing agent) was oxidized to form acetaldehyde and this acetaldehyde had an inherent unpleasant smell and was toxic [Text III-20 of 1983 Institute of Support and Development of Technical Research, Tochigi Prefectural Food Industry Advisory Committee (October 1984)].